Document Detail

The action of carbon dioxide on synaptic transmission in the cuneate nucleus.
MedLine Citation:
PMID:  4332379     Owner:  NLM     Status:  MEDLINE    
1. The excitability of synaptic structures in the cuneate nucleus was studied in eighteen decerebrate, unanaesthetized cats during acute changes in inspired P(CO2).2. Micro-electrode stimulation in the caudal half of the cuneate nucleus evoked antidromic and orthodromic responses which were recorded simultaneously from a forelimb nerve and from the medial lemniscus at the transected mid-brain surface.3. Increases in the concentration of inspired CO(2) (2-20%) progressively decreased the direct excitability of both the afferent fibre terminals (reflected in the antidromic potentials) and the cuneate relay neurones (reflected in the alpha wave of the orthodromic lemniscal response). Synaptically mediated responses, recorded as the beta component of the lemniscal potentials, were also depressed.4. The relation between input and output at the cuneate was determined by plotting antidromic against trans-synaptic (beta lemniscal) responses for different intensities of stimulation. The mean slope for logarithmic values of control potential amplitudes was 1.17 (+/- S.E. 0.13). It therefore appears that the transfer function for the cuneate is linear over a wide range.5. In the majority of experiments the input-output relation was unchanged or increased by raising P(CO2). It was concluded that the efficiency of synaptic transmission and release of transmitter appeared to be well maintained or possibly increased at individual active synapses during hypercarbia.6. The depressant action of CO(2) on afferent transmission can therefore be attributed largely to a block of impulse conduction in the primary afferent fibres.
M E Morris
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of physiology     Volume:  218     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1971 Nov 
Date Detail:
Created Date:  1972-03-17     Completed Date:  1972-03-17     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  671-89     Citation Subset:  IM    
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MeSH Terms
Carbon Dioxide*
Decerebrate State / physiopathology
Electric Stimulation
Forelimb / physiology
Hypercapnia / physiopathology
Medulla Oblongata / physiology*
Nerve Endings / physiology
Neural Conduction
Neurons, Afferent / physiology
Synapses / physiology*
Synaptic Transmission*
Reg. No./Substance:
124-38-9/Carbon Dioxide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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